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Mucosal immunity is critical to survival, with huge attention at present due to the Coronovirus pandemic. Epigenetic factors are increasingly recognized as important determinants of immune responses, and EZH2 closest to application due to the availability of highly-specific and efficacious antagonists. However, very little is known about the role of EZH2 in the myeloid lineage, with some conflicting reports. Here we show EZH2 acts in macrophages to limit inflammatory responses to activation, and selective genetic deletion results in a remarkable gain in protection from infection with the prevalent lung pathogen, pneumococcus. In contrast, EZH2 is required for neutrophil chemotaxis, and animals lacking neutrophil EZH2 show increased susceptibility to pneumococcus. In summary, EZH2 shows complex, and divergent roles in different myeloid cells, likely contributing to the earlier conflicting reports. Compounds targeting EZH2 are likely to impair mucosal immunity, however, may prove useful for conditions driven by pulmonary neutrophil influx, such as adult respiratory distress syndrome (ARDS).DigestEpigenetic control of mucosal immunity is important, and has translational relevance with the advent of inhibitor drugs now in the clinic for cancer indications. Here we show divergent role for EZH2 in macrophages and neutrophils. Loss of EZH2 in macrophages results in a gain of inflammatory and immune function, and protection from pneumonia. However, EZH2 is required for neutrophil chemotaxis, resulting in impaired anti-bacterial defence. We show that inhibition, or loss of EZH2 in macrophages results in a gain of immune function, with increased responses to infectious mimics such as LPS. However, the impact was far more dramatic in-vivo, with striking protection from the consequences of infection with pneumococcal bacteria. Loss of EZH2 resulted in a gain in activity of a number of inflammatory signaling cascades, including NFkB, PPARg, and IRFs1, and 7. This widespread macrophage re-programming varied between macrophages sites of origin, with the greatest impact seen in peritoneal macrophages which resulted in emergence of a new population of MerTK low cells. In contrast, in the neutrophils loss of EZH2 greatly impairs motility, and chemotaxis. This results in dramatic impairment of immune responses to the same pneumococcal infection. Extension of these studies to the mucosal epithelium revealed that EZH2 in bronchoalveolar epithelial cells had no impact on responses to infection with influenza. Taken together EZH2 plays diverse roles in the myeloid lineage, with profound impacts on inflammatory responses. The most striking observation was the difference seen between macrophages and neutrophils. EZH2 inhibition is likely to greatly impair mucosal immunity.Impact StatementHere we show a striking, but highly cell-type specific impact of the EZH2 methyltransferase on inflammatory, and anti-infective circuits; inhibition of EZH2 in macrophages augments macrophage cytokine production, but by impairing neutrophil migration impairs anti-bacterial responses.

Pulmonary airway epithelial cells (AECs) form a critical interface between host and environment. We investigated the role of the circadian clock using mice bearing targeted deletion of the circadian gene brain and muscle ARNT-like 1 (Bmal1) in AECs. Pulmonary neutrophil infiltration, biomechanical function, and responses to influenza infection were all disrupted. A circadian time-series RNA sequencing study of laser-captured AECs revealed widespread disruption in genes of the core circadian clock and output pathways regulating cell metabolism (lipids and xenobiotics), extracellular matrix, and chemokine signaling, but strikingly also the gain of a novel rhythmic transcriptome in Bmal1-targeted cells. Many of the rhythmic components were replicated in primary AECs cultured in air-liquid interface, indicating significant cell autonomy for control of pulmonary circadian physiology. Finally, we found that metabolic cues dictate phasing of the pulmonary clock and circadian responses to immunologic challenges. Thus, the local circadian clock in AECs is vital in lung health by coordinating major cell processes such as metabolism and immunity.—Zhang, Z. Hunter, L., Wu, G., Maidstone, R., Mizoro, Y., Vonslow, R., Fife, M., Hopwood, T., Begley, N., Saer, B., Wang, P., Cunningham, P., Baxter, M., Durrington, H., Blaikley, J. F., Hussell, T., Rattray, M., Hogenesch, J. B., Gibbs, J., Ray, D. W., Loudon, A. S. I. Genome-wide effect of pulmonary airway epithelial cell–specific Bmal1 deletion.

Recent studies reveal that airway epithelial cells are critical pulmonary circadian pacemaker cells, mediating rhythmic inflammatory responses. Using mouse models, we now identify the rhythmic circadian repressor REV-ERBα as essential to the mechanism coupling the pulmonary clock to innate immunity, involving both myeloid and bronchial epithelial cells in temporal gating and determining amplitude of response to inhaled endotoxin. Dual mutation of REV-ERBα and its paralog REV-ERBβ in bronchial epithelia further augmented inflammatory responses and chemokine activation, but also initiated a basal inflammatory state, revealing a critical homeostatic role for REV-ERB proteins in the suppression of the endogenous proinflammatory mechanism in unchallenged cells. However, REV-ERBα plays the dominant role, as deletion of REV-ERBβ alone had no impact on inflammatory responses. In turn, inflammatory challenges cause striking changes in stability and degradation of REV-ERBα protein, driven by SUMOylation and ubiquitination. We developed a novel selective oxazole-based inverse agonist of REV-ERB, which protects REV-ERBα protein from degradation, and used this to reveal how proinflammatory cytokines trigger rapid degradation of REV-ERBα in the elaboration of an inflammatory response. Thus, dynamic changes in stability of REV-ERBα protein couple the core clock to innate immunity.

Background Trichuriasis is a parasitic disease caused by the human whipworm, Trichuris trichiura. It affects millions worldwide, particularly in the tropics. This nematode parasite burrows into the colonic epithelium resulting in inflammation and morbidity, especially in children. Current treatment relies mainly on general anthelmintics such as mebendazole but resistance to these drugs is increasingly problematic. Therefore, new treatments are urgently required. Methods The prospect of using the retinoid X receptor (RXR) antagonist HX531 as a novel anthelmintic was investigated by carrying out multiple viability assays with the mouse whipworm Trichuris muris. Results HX531 reduced both the motility and viability of T. muris at its L3, L4 and adult stages. Further, bioinformatic analyses show that the T. muris genome possesses an RXR-like receptor, a possible target for HX531. Conclusions The study suggested that Trichuris-specific RXR antagonists may be a source of much-needed novel anthelmintic candidates for the treatment of trichuriasis. The identification of an RXR-like sequence in the T. muris genome also paves the way for further research based on this new anthelmintic lead compound. Electronic supplementary material The online version of this article (doi:10.1186/1471-2334-14-520) contains supplementary material, which is available to authorized users.